import javax.lang.model.element.NestingKind;

public class Main {
    abstract class Animal {
        String name;

        public Animal(String name) {
            this.name = name;
        }

        abstract public void eat();
    }

    class Dog extends Animal {
        int age;

        public Dog(String name, int age) {
            super(name);
            this.age = age;
        }

        public void eat() {
            System.out.println("吃骨头");
        }
    }
    public static void main(String[] args) {

        System.out.println("Hello world!");
    }
}